You might want to look in general for threads comparing fixed seat vs infant carrier, since this is essentially what you're asking. Here are some links:
www.mumsnet.com/talk/pregnancy/4720752-carseats-and-leaving-the-hospital
www.mumsnet.com/talk/car_seats_chat/4542472-newborn-baby-carrierpram-compatability-or-spin-seat-up-to-4yrs-old
www.mumsnet.com/talk/pregnancy/1399578-Which-type-of-carseat
www.mumsnet.com/talk/pregnancy/4407510-Car-Seats-Leaving-Hospital
www.mumsnet.com/talk/pregnancy/4242118-how-do-you-take-baby-home-from-hospital
A lot of these reference hospital but the discussion continues into general pros and cons.
It's commonly said that the 0-4 year seats are not as good for newborns e.g. don't fit them well or aren't as safe. IME, this is a bit of a myth and depends very much on the seat iteslf and the angle in your car. If you have sloped rear seats for instance you can struggle to obtain the correct recline angle for a newborn. Some also have a very large minimum position for the safety straps which is too big on most newborns. I don't have any experience of the Nuna Todl personally, so I can't say how well it specifically works for newborns. Perhaps you could go to a local retailer and ask their opinion/compare against other models. However, I will say it seems like a very expensive way to do it, and you're paying a lot here for quite normal standard features - the Todl is designed to fit onto the Next base only, which means you're looking at £350 for the seat plus £220 for the base - £570 in total, and you don't really need it to detach from the base because it doesn't go onto the pushchair for example. Most spin seats, suitable from birth, with their own base attached, offering the same functionality as the Nuna cost approximately half that. You can even get the Joie 360 Spin for around £200, and that is actually one of the better ones for newborn suitability (or at least used to be - the inserts are improving).
You might want to look at Besafe izi Turn B for example - this is probably the best 0-4 years spin seat in terms of newborn suitability, with really good positioning, great leg room for rear facing later and angle support for any slope of backseats. This also lasts until 4 years. (Be sure to get B version for the infant insert). It's expensive compared to other spin seats at £440 - but still cheaper than the Nuna with its base.
Or if you do have the full £570 to spend why stop at a seat which lasts to 4 years? Joie i-Prodigi is an isofix seat lasting rear facing until 22.5kg / 125cm (approx 6 years) and costs £575. Well worth comparing IMO. It doesn't spin, but that doesn't necessarily matter (Axkid One+ also worth comparing, though it's about £150 more.)
Another option to look at would be Besafe Stretch B - again with the excellent Besafe newborn insert ("B" version), lasts up to 125cm / 36kg (approx 7 years or longer) rear facing - this is the longest lasting, probably best/safest car seat in the world right now. No spin, and belt fitted - this is what allows it the much higher weight limit - this one is £510 and well worth considering if you do not need/want the convenience of an infant carrier.
Or Avionaut Sky. £380, suitable from birth, rear facing to 25kg / 125cm (though shorter, usually approx 115-120cm) - up to ~5-6 years - belt fitted no spin.